Greg Jennings sat out practice today, Mike McCarthy said he has a slight knee bruise but he hasn't been ruled out of the Indianapolis Colts game Friday night just yet.  Another receiver, 2nd round pick Randall Cobb, continues to sit as well with bruises to both knees.  McCarthy said he will be scratched this week.  So will defensive end Mike Neal with a knee sprain.  All three players who are cleaning out concussion cob webs will also stay home, Anthony Levine, C.J. Wilson and Lawrence Guy.  That will leave the Pack pretty thin along the defensive line Friday night.   For the second time this camp, free agent rookie wide receiver Tori Gurley has blocked a punt.  He's looked good on offense too with a 6-4 frame and long arms that has allowed him to swat a couple of Tim Masthay boots.  Running back Brandon Saine also blocked a punt.  Masthay said there were a couple of protection call miscues and it's nothing to get too wound up about considering it's like a Chinese fire drill with constant shuttling of special teams personel in camp.  First year linebacker Cardia Jackson showed up all day on possibly the warmest practice day of camp.  Temperatures brushed near 90 degrees with a thankful wind and Jackson was the hottest player on defense.  Jackson was a last day cut of the Rams last year and joined the Packers practice squad for the final regular season game.   The Louisiana-Monroe product made a terrific interception dropping in coverage and later hauled in a second pick when the pass was batted into the air at the line.  He also deflected away a couple of passes with good coverage.  Jackson is trying to crack the inside linebacking corps of starters AJ Hawk and Desmond Bishop with Robert Francois and rookie D.J. Smith running with the second team.